This invention is in the field of vibration and noise suppression and relates to vibration and noise suppression in a rotary drive train. More particularly, the invention relates to vibration and noise suppression by use of a vibration isolator in the rotary drive train.
In many drive applications, it is desired to reduce transmitted noise, such as gear noise, transmitted through a drive train in order to reduce the amount of noise being transmitted to the environment, as well as to reduce adverse effects of vibration on various parts. Vibration and noise control may be effected by vibration dampers and by vibration isolators. Vibration dampers control vibration primarily by converting the vibration motion into heat, whereas vibration isolators control vibration by reducing the ability of the system to transmit vibrations past the isolator. The present invention is directed primarily to vibration and noise control by use of a vibration isolator, although a certain degree of damping is also anticipated. The invention uses rubber, which is a common material for vibration isolation and has various advantages, including minimum effect of shape on resiliency of the isolating material (rubber). Rubber exhibits a fairly linear load-deflection response, particularly under shear loads.
A disadvantage of rubber is that it has a tendency to tear or separate, at bonded edges and within the rubber itself, under tensile loading. In general, failure under tensile load becomes a limiting factor in the use of rubber for transferring force. As with any vibration isolating system, rubber also is prone to decomposition. This decomposition is most likely to occur under abnormal heat conditions such as fire, although other factors such as chemical attack, can result in failure by decomposition.
In one type of vibration absorber, layers of rubber are bonded to interdigited metal discs associated alternately with driving and driven members of a drive shaft coupling. The rubber is subjected to substantially shearing loads. Decomposition of the rubber would allow the metal discs to freely rotate with respect to one another, in a manner similar to a released multiple-plate clutch. Tearing of the rubber bond with the metal would result in a tendency of the discs to slip, and therefore cause rapid deterioration of the rubber.
It is an object of this invention to provide a vibration and noise absorbing coupling for a power drive shaft, which is effective and reliable and which will continue to transmit power in emergency circumstances after a vibration absorbing media has been damaged. It is therefore desired to provide a vibration absorbing coupling in which rubber is used and is maintained under a compressive load so that drive forces transferred through the coupling have a reduced tendency to tear the rubber. It is further desired that the coupling be able to maintain its ability to transfer power under emergency circumstances, so that power can be transferred through the rubber when the rubber is partially deteriorated and power can be transmitted through the coupling when the rubber has completely deteriorated.